Method of and apparatus for combustion of fuels



Aug 1932- H. A. HYMER 1,869,897

METHOD OF AND APPARATUS FOR COMBUSTION OF FUELS Filed Nov. 1, 1926 4sheets-sheet 1 Aug. 2, 1932 H A. HYMER METHOD OF AND APPARATUS FORCOMBUSTION OF FUEL S Filed Nov. 1, 1926 gwue ntoz l M J W j M Aug. 2,1932. HYMER 1,869,897

METHOD OF AND APPARATUS FOR COMBUSTION OF FUELS Filed Ndv. 1, 1926 4Sheets-Sheet 5 32 \X Z 42 z 4/ 37 v 42 36 2 Q Willa/milling 1 W m nix i,8

Aug. 2, 1932. Y H. A. HYMER 1,869,897

METHOD OF AND APPARATUS FOR COMBUSTION OF FUELS Filed Nov. 1, 1926 4 seets-sheet 4 gym manic? Patented Aug. 2, 1932' HERBERT A. HYMER, OFDETROJ IT, MICHIGAN METHOD OF AND APPARATUS FOR COMBUSTIOIN F FUELSApplication" filed November 1, 1526, Serial No. 145,564.

This invention relates to fuel burners, and while I have illustrated asa preferred embodiment of my invention a burner employing a liquid fuel,it will be understood that .5 certain principles of the invention areapplicable to burners using gases or finely divided solid fuels as well;The preferred embodiment of my invention illustrated in the drawings isparticularly adapted for employ-ing fuel oil, and generally speaking.consists of means for first atomizing the liquid oil, mixing theresulting mist or atomized liquid with a combustion supporting medium,delivering this medium to a combustion chamber wherein the combustiontakes place. The parts are so designed and constructed that aparticular-1y efficient apparatus is provided which not only develops a very hightemperature, but also delivers a maximum number .of heat units for agiven quantity of fuel.

I have also employed a novel method of combustion which will behereinafter described, and the apparatus shown is particularly adaptedfor the carrying out of this method.

One object of my invention is to provide a new and improved method ofburning hydrocarbon fuels, such that the fuels will be burned in a veryeflicient manner and a high temperature developed therefrom.

Another object of my invention is the provision of an improved methodfor burning liquid fuels, such that a proper mixture 0 the fuel andcombustion supporting medium will be delivered to a combustion chamberand there burned in such a manner that a very high temperature willresult,'and an efficient combustion of the fuel will be effected.

Afurther object of my invention is the provision of an improved burnerfor hydro-carbon fuels, such that the fuel delivered to the burner willbe properly mixed with a combustion supporting medium, and thecombustion will take place under such conditions as will 5 cause a highdegree of temperature to be developed in the burner, and will effect anefficient combustion of the fuel in that an increased number of heatunits will be produced from a given quantity of fuel.

A still further object o my invention is to provide a burner of thischaracter of improved efficiency, wherein combustion will take place ata rapid rate and therefore a high temperature will be developed.

To these and other ends, the invention consists in the novelarrangements and combination of parts which will hereinafter bedescribed and claimed. l

( In the accompanying drawings:

Fig. l is a plan view of a burner, embodying my invention and adapted tocarry out my improved process;

Fig. 2 is an elevational view of the burner, taken at right angles withrespect to the View. shown in Fig. 1;

Fig. 3 is an end view of the burner, show ing the back or inlet endthereof;

Fig. 4 is an end view of the opposite end of the burner; I

Fig. 5 is a sectional view through the burner on line 55 of Fig. 2; i

Fig. 6 is anelevational view of the atomizer used'in connection with theburner;

Fig. 7 is a sectional view on line 77 of Fig. 6; v Y

Fig. 8' is an the atomizer Fig. 9 is a. side elevational view of theparts, shown in Fig. 8; FigfilO is a sectional view on line 10-10ofFig:9;. a

Fig. 11 is a view similar to Fig..10, but

elevational view of the end of takenjat a slightly different angle,namely,

on line 1111 of Fig. 8.

As shown in Fig. 1 of the drawings, the burner consists generally of anatomizer A,

a head B, a combustion shell C, and a shell casing or outer casing D.

As shown more particularly in Figs. 6 and 7 of the drawings, theatomizer consistsof a casing or body 10, having in the form shown threechambers 11, 12 and 13 separated by the partitions 14 and 15. Thechamber 11 is the oil chamber and is provided with a threaded inletopening 16 to receive an oil pipe. Air, or some combustion supportingmedium, is in like manner introduced into the chamber 13 through theinlet opening 17.

The partition 14 is provided with a threaded opening within which ismounted for at a needle valve seat member 18, having a valve seat 19 fora needle valve 20, provided upon the end of a stem 21, having threadedengagement with the stufling gland 22, which is in turn threaded intothe end of the body 10 to close the oil chamber. This stuffing gland isprovided with a flange 23 toabut the end of the body 10, and betweenthis flange and the end of the body may be interposed a sealing washer24. The valve stem 21 may be surrounded by a packing nut 25 threadedupon a boss 26 on the stufiing gland 22, and upon the end of the stemthere is provided a manipulating handle 27. The chamber 12 may beprovided with a plugged opening 28 for the insertion of an air gaugewhen desired.

The rear end of an oil tube 30 is mounted within the valve body 18, andextends forwardly therefrom, passing loosely through an opening in "thepartition 15, and throu h an opening 31 in the front wall 31 of t eatomizer body to project into the burner, as will be hereinafterdescribed. An oil delivery plug 32 is mounted in the front end of thistube and, as illustrated, has a threaded engagement therewith. The tube30 communicates with the valve seat 19 through a restricted passage 19*.

The opening 31 is considerably larger than the tube 30, and threadedlymounted in this opening is a primary air tube 33 which surrounds thetube 30, the tube 33 being of such size that a considerable spaceremains between its inner surface and the outer surface of the tube 30,for the passage of air. Secured at the end of the air tube 33 is aprimary air cap 34, which at its forward end has a reduced opening 35approxi mately the same size as the tube 30, so as to permit theadjacent end of the latter tube to be received in this opening andthereby supported in proper position. This reduced openin at the end ofthe cap 34, provides flickening of the metal of the wall of the cap atthat point, and within this thickened wall are arranged a number oflongitudinal air delivery openings 36, communicatin with the interior ofthe cap 34, and likewise, with the space between the oil tube 30 and theprimary air tube 33. As shown in Fig. 8 of the drawings, six of theseopenings are provided, although it will, of course, be understood thatthis number may be varied. Between these openings, the metal is cut awayat the exterior surface of the cap to provide relief passages 37 asshown in Figs. 5, 6, 9 and 11, and leaving ribs or ridges 38 betweenthese passages and about the openings 36.

The oil plug or tip 32 is somewhat conical in shape, and is providedwith a central longitudinal oil passage 40. A number of radiallydisposed openings 41 are provided intermediate the ends of the plug ortip, and

neeaeev communicate with the passage to permit the delivery of a sprayof oil to the atomizing air. Rea-rwardly of and adjacent to the openings41 is provided an inclined shoulder or apron 42, which projects slightlyfrom the adjacent surface of the oil spray plug and shields the openings41.' The longitudinally disposed passage 40 is continued to the tip endof the plug 32 and forwardly of the openings 41 provides a passage 43for the admission of air in a rearward direction, as will be hereinafterexplained.

The end of the air cap 34, and likewise the oil spray plug 32 areadapted to be inserted into the bore of a Venturi member 44, which issupported by the head of the burner, as will be hereinafter described.

Adjacent its forward end, the atomizer body 10 is provided with a flange45' to abut against and be secured to the flange 46, at the rear end ofthe head B. This head is hollow and is provided in the form shown withan interior air chamber 47 and a rear opening 48 through which the airtube 33 is received, about which opening a boss or projection 49 offrusto-co'nical shape is formed on the rear inner surface of the head.or spider 50 is provided at the frontpart of the head through which anumber of openings 51 are formed. Between these openings, afrusto-conically shaped boss 52 projects forwardly from the web 50,which boss has a skirt portion 53 projecting rearwardly into the chamber47, and over and in spaced relation to the boss 49. The Venturi member44 is seated in the open end of the boss 52, the assembled relation ofthese parts, together with the oil spray plug 32 and the air cap 34being shown more particularly in Fig. 5.

The head B is provided with a laterally projecting neck 55, having anair opening 56 covered by a shutter 57 pivotally secured at 58 to thewall of the neck. A manipulating pin 59 is arranged on the shutter bywhich it may be moved to admit the desired quantity of air. It will beunderstood that in some of the uses of the burner, the shutter 57 willremain entirely closed, but as will be hereinafter explained, in certaininstances, it may be desirable to admit a certain amount of air throughthis opening into the chamber 47. I

The combustion shell or chamber C, shown more particularly in Fig. 5, issecured at its rear end to the web 50 by bolts 60, these bolts passingthrough spacing members 61 to maintain the shell in proper positionrelatively to the head. The shell is provided with a somewhat contractedfront end 62, of substantially cylindrical shape, which from a point 33is enlarged to form a portion 64,

substantially of an ellipsoidal shape, the shell contracting againadjacent the point 65 and A web thereafter expanding toward its rearend.

the opening is provided an entraining frustocone shaped sleeve 66,terminating in a substantially cylindrical front portion 67 throughwhich the charge of mixed fuel and air is delivered into the ellipsoidalportion 64 of the combustion chamber.

In the outer wall of the shell and at the rear end thereof are providedignition openings 68, which are disposed substantially opposite toignition openings 69 in the outer or shell casing D. This shell casingsurrounds the combustion shell C and substantially conforms thereto inshape, having an ellipsoidal intermediate portion 70, a contractedportion adjacent its forward end 71, and a contracted portion 72adjacent the openings 69- Behind the openings 69 the outer shellisslightly expanded and termi-..

nates in an annular flange 73 which is secured by bolts 74 to the flange7 5 of the head. Adjacent the forward end portion of the outer casingare provided a number of air openings 76 for the admission of air to thecasing about the combustion shell C, as will be hereinafter explained.The forward end of the casing D is slightly expanded beyond the openings7 6 and at the extreme outer end is provided with an internallyprojecting flange 7 7, the inner edge of which lies closely adjacent theouter surface of the forward portion 62 of the shell C. The flange 77 isnotched ata number of points about itsperiphery, as shown at 7 8,whereby additional openings for the admission of air thereinto areprovided As shown in Fig. 10, the bore of the Venturi member 44 has aconstricted-central portion, as shown at 44 behind which it flaresoutwardly so that the bore is considerably larger adjacent the inner endthereof at 44.

Between these points it is substantially frusto-conical in shape, andgenerally speaking parallels the outer surface of the oil-plug 32 for apart of its length. Beyond the contracted portion 44 the bore of theVenturi member again flares outwardly to its mouth The shape of the boreof the Venturi member just described is adapted to bring about athorough and intimate mixture of the fuel and combustion supportingmedium before the charge is delivered to the combustion chamber.

The oil plug 32, as clearly shown in Figs. 9 to 11, is tapered towardthe forward end so that it terminates in a relatively small end surfaceand is so designed as to provide a streamline body effect. This shape ofthe oil plug is conducive to the free passage of air and fuel thereaboutand prevents the formation of a partial vacuum at the end thereof suchas would be caused if the plug were provided with a blunt end, and thecharge which is directed inwardly across the outer end of the passage 43in effect brings about a pressure at the mouth of this passage such thatinconjunction with the reduction of pressure in passages 40-and 43 in amanner to be hereinafter pointed out causes air to pass into the passa ein a direction .opposite to that of the fuel owing through the passage40, which air mixes with the fuel and assists in the atomizing thereof.

As shown in the drawings, the radially disposed openings 41 arepreferably equal in number to the air passages 36, and. register withthese passages. This is clearly shown in Fig. 9 where one of theopenings 41 is shown directly registering with the center of one of theribs 38 through which an opening 36 is formed. By this arrangement theair passing through the opening 36 will flow directly over one of theopenings 41 so that an efficient mixture and atomizing of the air andfuel is effected.

In the operation of my device, it will be understood that oil isintroduced into the chamber 11. through the opening 16, and likewise theopening 17 is connected to a source of compressed air. The oil isintroduced into theopenings 16 under a certain amount of pressure, whichpressure will be suflicient to cause the oil to pass through the oiltube 30 and issue through the openings 41 in the oil plug 32, the oilbeing thus broken up into relatively small streams. The air supplied tothe chamber 13 will also be under pressure, which pressure may varyaccording to dred or more pounds per square inch. I With enlargedopenings in the air cap 34 the burner may operate with as low a pressureas eight ounces per square inch. The air passes through the air tube 33into the cap 34 and through the openings 36 impinging upon, mixing with,and serving to atomize the oil flowing through theppenings 41. The oilplug is thus surrounded by the air currents coming from the openings 36which, being under pressure, will also have a tendency to entrain anddraw the oil through the openings 41 thus causing a reduction ofpressure therein and in the passage 40. Due to the difference inpressure existing at the tip of the oil plug 32 and in the passage 40and openings 41, a mixture of air and oil will flow rearwardly throughthe passage 43, meeting and mixing with the oil entering the plugthrough the passage 40, and passing out through the openings 41 togetherwith the 'Ih1s tends to break up the oil stream. spreading ormushrooming it' out, and assisting in the atomizing and mixingoperations. The air rushing out of the openings 36 passes over thecollar 42 which shieldsthe oil openings 41 and prevents a tendency ofthe pressure of the air to impede the issuance of the oil through theseopenin s. It may be stated, however, that while have found that theoperation of the burner is improved by the provision of this collar, itis conditions from a few pounds to one hunnot absolutely essential, andthe burner may in some instances be operated without it.

The passage of the air through the bore of the Venturi member from thepassages 36, serves to draw in .additional air through the reliefpassages 37 from the interior of the frusto-cone shaped boss 52 andapron 53. This air is drawn from the chamber 47, and most of it entersthis chamber through the openings 76 adjacent the end of the shellcasing D. The air entering through these openings passes between thecombustion shell C and the outer shell D for substantially the entirelengthof the outer shell, and as the combustion shell C is very hotduring the operation of the burner this air is preheated to a relativelyhigh temperature, and also serves to cool the combustion shell to enableit to withstand the high temperature developed therein. In passingthrough the chamber 457 and about the apron 53 it is cooled to someextent before it is permitted to impinge uponthe-air tube 33. Thiscooling of the air before it is permitted to enter the Venturi memberavoids any possibility of ignition or combustion at a point too low inthe burner and before the charge is delivered to the combustion shell,for it is of course recognized that the more concentrated the combustionor the more confined the combustion zone the higher the degree oftemperature which will be developed, as compared with a conditionwherein partial combustion may take place over a relatively great areauntil the fuel may be entirely consumed. Likewise the frusto-cone shapedboss or projection 49 about the opening 48 of the head prevents this airimpinging upon the rear end of the tube 33, and serves to direct itforwardly within the apron 53 after ithas been somewhat cooled bycontact with the wall of the head B, so as to avoid a possibility ofoverheating the atomizing air within the tube 33.

' Additional air may in some instances be admitted to the chamber 47through the shutter 57. This air is prevented by the apron 53 frompassing into the Venturi member until it is mixed with the preheated airin the chamber 47. The amount of air permitted to enter past the shutter57 depends upon the conditions under which the burner is used. Forinstance, if the shutter 57 is closed and all of the air used by theburner is drawn through the openings 76, this air will serve to cool thecombustion shell C, and will cause the combustion to take place nearerthe forward end of this shell.

' If the shutter 57 is opened less air will be drawn through theopenings 76, and as a result the combustion shell will become hotter,and this will cause the combustion to take place closer to the end ofthe Venturi member 44. It is, of course, desirable to permit the burnerto receive as much air as possible through the openings 76 and opening56, in order to cut down as far as possible the amount of compressed airnecessary, as the production of the latter is an item of expense. Whenthe burner is used in connection with a furnace, as shown in Fig. 2, itis usually desirable to only partially open the shutter 57 in order topermit a large quantity of the indrawn atmospheric air to enter throughthe openings 76 in order to cool the combustion shell as much aspossible.

We have, therefore, issuing from the Venturi member a charge consistingof a mist of atomized air and oil in a substantially thoroughly andintimately mixed condition. This charge is permitted to expand in theforward end of the Venturi tube, and while its velocity is therebyincreased its pressure is decreased. lVhile passing through the member67 more air is entrained through the cone shaped sleeve 66. To a largeextent this air passes about the spacing members 61 and comes directlyfrom the space between the outer and inner shells, without first passinginto the chamber 47 and, like the air drawn through the relief passages37, has been preheated, but even to a greater extent than the latter.This air is likewise directed across the mouth of the Venturi tube, andis thereby mixed with the charge issuing therefrom. This mixed charge offuel and air enters the ellipsoidal portion 64 of the combustionchamber, where the charge is caused to burn under pressure within aconfined space, and is burned so rapidly that it may be described as anexplosive combustion; that is, when the charge enters the confiningcombustion chamber in the proper proportions the combining of the fueland oxygen takes place substantially instantaneously,'and the result isthat an explosion or multiplicity of explosions occur rather than aquiet or flash burning of the fuel. It is also due to the initialpressures with which the fuel and air are introduced into the burner,the passage of the charge through the combustion chamber beingresistedby the pressure waves set up by the explosions within the shell, thewaves being reflected from the ellipsoidal wall of this chamber so as tocause a turbulence of the charge therein, which also adds to thepressure of the mixture and assists in keeping the charge within thechamber a suflicient length of time to be completely burned. The backpressure due to the combustion is borne to some extent by the restrictedportion of the shell, and likewise the forward pressure is borne by therestricted portion 63. The result is, therefore, that combustion takesplace at a very high rate of speed and develops a very high temperature.

Some air may also be drawn into the burner through the ignition openings69, al-

though these openings are of relativelv f smaller area than the combinedareas of openings 7 6 and 78, and the pressure within the combustionshell under ordinary conditions probably prevents the entry of any greatquantity of air through these openings. -In fact under some conditionsof adjustment flame will issue therefrom showing that the pressureadjacent thereto is greater and not less than atmospheric pressure.Furthermore, as shown in Fig. 5 of the drawings, the construction of thecombustion chamber or shell C is such that opposite the openings 69 itis close to the inner surface of the shell D, while between the openings69 the shell'C is relatively widely spaced from the shell D, thuspermitting the free flow of air between shells C and D into the chamber47 and frusto-conical shaped sleeve 66.

As the air necessary to support combustion is admitted within the burnerand, therefore, the charge does not have to issue from the mouth of theshell C in order to mix with the surrounding air before being burned,combustion of the charge takes place within the combustion shell C. Thezone of combustion begins adjacent the forward end of the member 67, andextends forwardly from this point into the contracted cylindrical end 62of the combustion shell.

The combustion shell C is preferably made sufficiently long so thatsubstantially complete combustion of the fuel takes place within thischamber. The cross-sectional size of this shell is such that the chargeis confined between the walls thereof, and the explosive waves beingreflected from the walls creates the turbulence heretofore referred towhich aids in keeping the charge within the combustion chamber or shelluntil it is substantially completely burned. It will be seen, therefore,that the length of the shell depends somewhat'upon thepoint at whichcombustion begins to take place: that is, the further the beginning ofcombustion in front of the Venturi member the longer the tube must be inorder that unburned gases do not issue therefrom. In some instances,such as when the burner is used with a furnace, it is not alwaysundesirable to have a small amount of the charge burned without thecombustion shell, and this may be regulated by controlling the supply ofair and fuel. I believe, however, that the most efficient con-. ditionsprevail and the highest temperature is developed when completecombustion takes place before the charge leaves the shell. Un-

der ordinary circumstances the length of the combustion shell should benot less than three times its diameter at the ellipsoidal portion.

It will be noted that the Venturi. member 44 projects forwardly from theoil spray plug 32. so that after the air issuing through the openings 36and through the relief passages 37 meets the oil issuing from theopenings 41 a passage or chamber is provided within the Venturi tubewherein the oil and air may mix before passing into themember 67 fordelivery to the combustion chamber. By confining the air and oil withinthe Ven turi tube at this point, and on account of the turbulencecreated within this passage in the tube a more intimate mixture of thefuel and combustion supporting medium, which is preheated, is effected.By this arrangement a finely divided mist or supply of fuel and air isdelivered to the combustion chamber ready to be exploded upon reachingthe combustion zone.

In lighting the burner it is usual to admit at first a limited quantityof fuel and air, the supply of fuel of course being regulated by theneedle valve 20. A flame is then applied to the ignition opening 69, andthe charge lighted. The supply of fuel and air can then be increased tothe desired extent to meet the conditions under which the burner isused.

It will be apparent that the air in the air chamber 13 will passrearwardly into the chamber 12 about the tube 30, and the air pressurecan be readily measured by the removal of the plug 28 and thesubstitution of an air gauge therefor. v r

I have shown and described, as a preferred embodiment of my invention, aburner designedto use a liquid or finely divided solid fuel whichemploys the same general principles employed by the gas burner shown anddescribed in my copending application, Serial No. 23,109, filed January27, 1925, but it will be understood that my invention is not limited toall the details shown, but is capable of modification and variationwithin the spirit-of the invention and within the scope of the appendedclaims. For instance, it has been determined that by removing the oilplug 32from the end of the tube 30 the burner shown in this applicationis admirably adapted for using natural gas as a fuel, and without otherchanges will burn this gas in a very eficient manner. The oil plug mayof course readily be removed, due to its threaded connection with thetube by which it is supported.

What I claim is:

1. A burner for liquid fuels, comprising a fuel supply tube havinglaterally directed outlets for the fuel, an air supply tube, said airsupply tube directing a current of air peripherally about the fuelsupply tube to meet and mix with the issuing fuel streams, a

1 member having a passage therethrough, positioned on said air supplytube and enclosing said air and fuel outlet openings, .and said airsupply tube having relief cuts therein communicating with the passage insaid member to permit atmospheric air to enter said passage between themember and the air supply tube.

2. In a burner for liquid fuels, a fuel supply member comprising a plughaving a lon- Mill) of said plug also tapering forwardly in front ofsaid shoulder.

4. In a burner for hydrocarbon fuels, a fuel supply tube having a fueloutlet adjacent one end thereof, a hollow member into the. passage ofwhich the outlet end of said tube is inserted, an air delivery membersurrounding the fuel supply member and likewise inserted into thepassage of said hollow member, said air supply member having outletopenings directed into said passage and having relief cuts on itsexterior surface also communicating with said passage.

5. In a burner for hydrocarbon fuels, a

fuel supply tube having a fuel outlet adjacent one end thereof, a hollowmember into the passage of which the outlet end of said tube isinserted, an air delivery member surrounding the fuel supply tube andlikewise inserted into the passage of said hollow member, said airdelivery member having outlet openings directed into said passage, thewall of said air delivery member fitting closely the hollow member andthere being provision for the entry of air between the walls of saidhollow member and said air delivery member.

6. A. burner for hydrocarbon fuels comprising a hollow head memberhaving a chamber therein, a combustion chamber adjacent the head, anouter shell surrounding the wall of the combustion chamber inspacedrelation thereto, the space between said wall and shell being incommunication with the head chamber, said shell being provided with airopenings and said head being provided with an air inlet opening, meansto induce a flow of air from said head chamber into the combustionchamber, and means to regulate the flow of air through said last namedopening into said head.

7 A burner for hydrocarbon fuels comprising a chambered head member, afuel and airmixing device supported by said head member, a combustionshell adjacent the head member and receiving the charge from said mixingdevice, means for subjecting air to the temperature of the combustionshell, said head chamber having openings for receiving the heatedatmospheric air and an additional intake opening for receiving unheatedair, and means for causing the fuel to be mixed with the chamber airbefore passing into the combustion chamber.

8. A burner for hydrocarbon fuels comprising a chambered head member, afuel and air mixing device supported by said head member, a combustionshell adjacent the head member and receiving the charge from said mixingdevice, means for subjecting air to the temperature of the combustionshell, said head chamber having openings for receiving the heatedatmospheric air and an additional intake opening for receiving'unheatedair, means for causing the fuel to be mixed with the chamber air beforepassing into the combustion chamber, and means to cause the charge toentrain preheated air directly from the space about the shell.

9. A burner for hydrocarbon fuels comprising a chambered head member, acombustion shell mounted adjacent the head member and an outer shellsurrounding the combustion shell in spaced relation thereto, said spacebeing in communication with the head chamber and also with thecombustion shell, means for passing a supply of fuel and air through thehead chamber into the combustion shell, and means to cause the supply offuel and air to entrain during its passage preheated air from thechamber in said head member and also preheated air directly from thespace between the combustion and outer shells.

10. In a burner for hydrocarbon fuels, a chambered head member havingopenings at the front surface thereof, a combustion chamber having awall thereof mounted adjacent said openings, a casing mounted on saidhead member and surrounding said combustion chamber whereby air enteringthe head member through said openings is subjected to the temperature ofthe wall of the chamber, the head chamber having an additional air inletopening, means to conduct a supply of fuel and air through said headchamber to the combustion chamber, means to cause said supply to entrainadditional air from the head chamber, and means to cause the airentering said head chamber throughv said additional opening to be mixedwith the preheated air entering the head chamber through the first-namedopenings before being entrained by the supply of fuel and air.

11. A burner for hydrocarbon fuels comprising a chambered head member, acombustion shell mounted adjacent said head member, means for supportinga fuel and air mixing device from the head member, a hollow taperedmember supported by the head into which the mixing device extends, saidmixing device being in communication with the interior of said hollowtapered member to entrain air from the interior thereof, means topreheat air by the combustion shell, said head chamber having openingsadjacent the combustion shell to admit air heated unheated atmosphericair,

' shell having a tapered member surroun unease? thereby, and anadditional opening to admit unheated air and said tapered member havinga skirt portion adapted to cause the heated and unheated air to mixbefore passing to the mixing device. 7

12. A burner for hydrocarbon fuels comprising a chambered head memberhaving supported adjacent the front face thereof a tapered hollowmember, a combustion shell supported adjacent the head member, a fueland air mixing device supported Within said hollow tapered member andextending to the smaller end thereof, means for conducting air about thecombustion shell into the chamber of the chambered head member, the airbeing preheated by the combustion shell, means for admitting unheatedatmospheric air into the chamber, said mixing device entraining air fromsaid interior of said hollow tapered member, unheated air intake toprevent direct passage of such air to the interior of the hollow mem-.ber.

13. A burner for hydrocarbon fuels comprising a chambered head memberhaving supported adjacent the front face thereof a tapered hollowmember, a combustion shell supported adjacent the head member, a fueland air mixing device supported within said hollow tapered member andextending to the smaller end thereof, means for preheating air by thecombustion shell, said head having means for admitting to its chambersuch air preheated by the combustion shell and also said mim'ng deviceentraining air from said interior of said hollow tapered member, saidtapered hollow member having a skirt portion extending rearwardly infront of the intake opening but terminating short of the chamber wall topermit communication between the interior of such memberand the headcham- 14. In a burner for hydrocarbon fuels, a

head, an outer casing supported by the head, a combustion shellsupported. by the head within said casing and spacing-members to spacesaid shell from the front surface of the head, a hollow taperedmember-supported at the front surface of the head and extending into thecombustion shell and said combustion ..shell from the front surface anda baffle adjacent the and in spaced relation to the end of said firstnamed tapered member, the passages formed interiorly of said taperedmembers being in communication with the interior of the head, and meansto introduce a mixed charge of fuel and air from said first namedtapered member through said last named tapered member into thecombustion shell.

16. In a burner for hydrocarbon fuels, a head, a casing supported by thehead, a combustion shell supported by the head within the casing,spacing members to space said of the head, a hollow tapered membersupported at the front surface of the head and extending into thecombustion shell, means for discharging a combustible mixture throughsaid tapered member into the combustion shell, and said combustion shellhaving a tapered member surrounding and in spaced relation to the end ofsaid first named tapered member, the'space between said tapered memberscommunicating with the space between the combustion shell and thecasing, the combus tible mixture discharged through said first namedtapered member entraining air from the space between said taperedmembers, and said first named tapered member having a skirt portionextending rearwardly into the head. I

In witness whereof, I have hereunto set my hand this 27 day of October,1926.

HERBERT A. HYMER,

shell having a tapered member surrounding v and in spaced relation tothe end of said first named tapered member, the passages formedinteriorly of said tapered members being in communication with theinterior of the head.

15. In a burner for hydrocarbon fuels, a

head, an outercasing supported by the head,

a combustion shell supported by the head within said casing andspacingmembers to space said shell from the front surface of the head, ahollow tapered member supported at the front surface of the head andextending into the combustion shell and said combusaiign

